Mathematics

Problem

The cumulative frequencies of the monthly electricity consumption (in kWh) of 40 households are given below.

Consumption (kWh)	100–120	120–140	140–160	160–180
Cumulative frequency	7	18	32	40

Calculate the median consumption (in kWh). a)

150\text{ kWh}

142.9\text{ kWh}

143.6\text{ kWh}

141.4\text{ kWh}